title: Herpes simplex virus type 1 single strand DNA binding protein and helicase/primase complex disable cellular ATR signaling.
abstract: Herpes Simplex Virus type 1 (HSV-1) has evolved to disable the cellular DNA damage response kinase, ATR. We have previously shown that HSV-1-infected cells are unable to phosphorylate the ATR substrate Chk1, even under conditions in which replication forks are stalled. Here we report that the HSV-1 single stranded DNA binding protein (ICP8), and the helicase/primase complex (UL8/UL5/UL52) form a nuclear complex in transfected cells that is necessary and sufficient to disable ATR signaling. This complex localizes to sites of DNA damage and colocalizes with ATR/ATRIP and RPA, but under these conditions, the Rad9-Rad1-Hus1 checkpoint clamp (9-1-1) do not. ATR is generally activated by substrates that contain ssDNA adjacent to dsDNA, and previous work from our laboratory has shown that ICP8 and helicase/primase also recognize this substrate. We suggest that these four viral proteins prevent ATR activation by binding to the DNA substrate and obstructing loading of the 9-1-1 checkpoint clamp. Exclusion of 9-1-1 prevents recruitment of TopBP1, the ATR kinase activator, and thus effectively disables ATR signaling. These data provide the first example of viral DNA replication proteins obscuring access to a DNA substrate that would normally trigger a DNA damage response and checkpoint signaling. This unusual mechanism used by HSV suggests that it may be possible to inhibit ATR signaling by preventing recruitment of the 9-1-1 clamp and TopBP1.
authors.affiliation: Department of Molecular, Microbial and Structural Biology and the Molecular Biology and Biochemistry Graduate Program, University of Connecticut Health Center, Farmington, Connecticut, United States of America.
authors.forename: Kareem N
authors.initials: KN
authors.lastname: Mohni
authors.forename: Samantha
authors.initials: S
authors.lastname: Smith
authors.forename: Alexander R
authors.initials: AR
authors.lastname: Dee
authors.forename: April J
authors.initials: AJ
authors.lastname: Schumacher
authors.forename: Sandra K
authors.initials: SK
authors.lastname: Weller
mesh_terms: D000818:Animals; D064007:Ataxia Telangiectasia Mutated Proteins / Q000235:genetics / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D002522:Chlorocebus aethiops; D004265:DNA Helicases / Q000235:genetics / Q000378:metabolism*; D019915:DNA Primase / Q000235:genetics / Q000378:metabolism*; D004279:DNA, Viral / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005092:Exonucleases / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D018259:Herpesvirus 1, Human / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D014709:Vero Cells; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D004279:DNA, Viral; D004268:DNA-Binding Proteins; C462949:HUS1B protein, human; C045462:ICP8 protein, Simplexvirus; D009687:Nuclear Proteins; C110513:TOPBP1 protein, human; D014764:Viral Proteins; C069930:rad9 protein; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D019915:DNA Primase; D005092:Exonucleases; C113574:Rad1 protein, human; D004265:DNA Helicases